1. Field of the Invention
This invention relates to radar and sonar and more particularly to finding both conventional and stealth-modified targets by these means.
2. Prior Art
Radar and sonar equipment and techniques are well developed and widely used both militarily and otherwise, and the literature on these subjects abounds. Skolnik, for example, lists over one thousand references in his Introduction to Radar Systems, and his Radar Handbook covers the subject in even more detail.
Military and non-military applications differ, however, because enemy targets are attacked when detected and so best survive when they are hard to find, and are modified to make them so, while non-military targets survive best when they are detected before there is any risk of collision, and are modified accordingly. While the most refined techniques for making military targets stealthy and the techniques for finding them despite stealth presumably have not been made public, it is clear that, at least with respect to detection of stealthcraft with prior art radars or sonars, this task becomes more difficult when these targets are absorbers rather than reflectors of the beams transmitted to find them, and this task has been made so, at least in part, by the conventional techniques used to suppress background returns.